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Javier Arranz-Andrés,Inmaculada Suárez,Rosario Benavente,Ernesto Pérez 한국고분자학회 2011 Macromolecular Research Vol.19 No.4
Two series of ethylene-propylene copolymers were synthesized in the whole composition range using a metallocene catalyst, one in the homogeneous phase (H copolymers), and the other with the catalyst supported in silica (S copolymers). Some differences were found between the two groups. Therefore, the amount of ethylene needed to obtain a certain proportion of the γ form is lower in the H than in S series. Moreover, the composition to obtain the pseudo hexagonal form is also different for the two groups. On the other hand, degree of crystallinity, crystal sizes and microhardness values display a similar variations with the comonomer content of the two series. Consequently, from a macroscopic point of view, materials with similar macroscopic mechanical properties can be produced using both supported and homogeneous metallocene catalysts despite the structural differences.
Marta Díaz,Eva Epelde,Andrés T. Aguayo,Javier Bilbao 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-
The capacity of HZSM-5 zeolite (SiO2/Al2O3 ratio = 30–280) based catalysts with a hierarchical porousstructure has been explored for the oligomerization of 1-butene at low pressure. Catalysts werecharacterized (structural, physical and acid properties) and tested in afixed bed reactor under thefollowing conditions: 1.5 bar; 175–325 C; space time, 0.5–10 gcatalyst h (molC) 1; butene partial pressure,0.375–1.5 bar; time on stream, 10 h. Results were evaluated with the aim of boosting naphtha (C5-C12=)fraction. A good compromise between conversion (62% in C units contained) and naphtha yield (42%) wasachieved by using a HZSM-5 zeolite with SiO2/Al2O3 = 30 at 275 C and 6 gcatalyst h (molC) 1, where 23%corresponds to C8-C12= and 19% to C5-C7=, respectively. Furthermore, the hierarchical porous structurefacilitated catalysts to tend to a pseudo-stationary deactivation state after 2–3 h time on stream, whichcould be interesting for process scale up.
Sorafenib resistance in hepatocarcinoma: role of hypoxia-inducible factors
Carolina Méndez-Blanco,Flavia Fondevila,Andrés García-Palom,Javier González-Gallego,José L. Mauriz 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-
Sorafenib, a multikinase inhibitor with antiproliferative, antiangiogenic, and proapoptotic properties, constitutes the only effective first-line drug approved for the treatment of advanced hepatocellular carcinoma (HCC). Despite its capacity to increase survival in HCC patients, its success is quite low in the long term owing to the development of resistant cells through several mechanisms. Among these mechanisms, the antiangiogenic effects of sustained sorafenib treatment induce a reduction of microvessel density, promoting intratumoral hypoxia and hypoxia-inducible factors (HIFs)-mediated cellular responses that favor the selection of resistant cells adapted to the hypoxic microenvironment. Clinical data have demonstrated that overexpressed HIF-1α and HIF-2α in HCC patients are reliable markers of a poor prognosis. Thus, the combination of current sorafenib treatment with gene therapy or inhibitors against HIFs have been documented as promising approaches to overcome sorafenib resistance both in vitro and in vivo. Because the depletion of one HIF-α subunit elevates the expression of the other HIF-α isoform through a compensatory loop, targeting both HIF-1α and HIF-2α would be a more interesting strategy than therapies that discriminate among HIF-α isoforms. In conclusion, there is a marked correlation between the hypoxic microenvironment and so
Reaction network of the chloromethane conversion into light olefins using a HZSM-5 zeolite catalyst
Monica Gamero,Beatriz Valle,Pedro Castaño,Andrés T. Aguayo,Javier Bilbao 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.61 No.-
The second step of chlorine-mediated methane valorization into hydrocarbons has been investigated using a HZSM-5 zeolite catalyst. A parametric study has enabled to set the reaction network, which is dominated by the dual cycle mechanism and secondary reactions of light olefins. This network explains the formation of methane, light olefins, C5+ aliphatics, paraffins, aromatics and coke. Under the optimal conditions, the light olefin selectivity is >70%, of which >40% corresponds to propylene. Coke is originated in the zeolite micropores and then grows within the matrix meso- and macropores.
Rafael Van Grieken,Guillermo Calleja,Inmaculada Suarez,Javier Arranz-Andrés 한국고분자학회 2013 Macromolecular Research Vol.21 No.2
The slurry polymerization reactors on the industrial scale operate in continuous mode at low monomer conversion per pass to minimize mass and heat transfer limitations. Nevertheless, for the screening of catalytic systems,the laboratory tests are carried out using batch or semi-batch reactors. In this work, ethylene/propylene copolymers were synthesized in a semi-continuous reactor under similar conditions, where the only difference involves the modification of the feed ratio during the reaction. The key point of the control system is a micro-gas chromatograph (MGC), which analyzes the molar ratio ethylene (C2) to propylene (C3) in the gas phase during the reaction, and the composition in the liquid phase was calculated using the Soave-Redlich-Kwong equation of state. The effect of the ethylene/propylene copolymer microstructure has been studied using different techniques that allow us to conclude that the method of synthesis influences the comonomer distribution and the final copolymer properties.
The erector spinae plane block: a narrative review
Pablo Kot,Pablo Rodriguez,Manuel Granell,Beatriz Cano,Lucas Rovira,Javier Morales,Ana Broseta,Jose De Andrés 대한마취통증의학회 2019 Korean Journal of Anesthesiology Vol.72 No.3
Regional anesthesia and pain management have experienced advances in recent years, especially with the advent of fascial plane blocks. The erector spinae plane block is one of the newest techniques to be described. In the past two years, publications referring to ESP block have increased significantly. The objective of this review is to analyze the articles about ESP block that have been published to date. We performed a search in the main databases and identified 368 articles. After a selection of the relevant articles, 125 studies were found eligible and were included in the review. The ESP block is performed by depositing the local anesthetic in the fascial plane, deeper than the erector spinae muscle at the tip of the transverse process of the vertebra. Many cases of its use have been described with satisfactory results in the treatment of both acute pain and chronic pain. The applicability of the technique covers many clinical scenarios. Of the 98 case reports reviewed, 12 and 87 articles, respectively described the technique as a treatment for chronic pain and acute pain. The single-shot was the most frequently used technique. As described in the articles published to date, the technique is easy to perform and has a low rate of complications. However, despite the effectiveness of the technique, further studies are necessary to obtain more evidence of its actions.
Ríos-Osorio Néstor,Muñoz-Alvear Hernan Darío,Jiménez-Castellanos Fabio Andrés,Quijano-Guauque Sara,Jiménez-Peña Oscar,García-Perdomo Herney Andrés,Caviedes-Bucheli Javier 대한치과보존학회 2022 Restorative Dentistry & Endodontics Vol.47 No.3
Objectives This systematic review and meta-analysis aimed to assess the association of cigarette smoking with the prevalence of post-endodontic apical periodontitis in humans. Materials and Methods We searched through PubMed/Medline, Web of Science, and Scopus from inception to December 2020. Risk of bias was performed by using the Newcastle-Ottawa Scale for cross-sectional, cohort, and case-control studies. We performed the statistical analysis in Review Manager 5.3 (RevMan 5.3). Results 6 studies met the inclusion criteria for qualitative and quantitative synthesis. Statistical analysis of these studies suggests that there were no differences in the prevalence of post endodontic apical periodontitis (AP) when comparing non-smokers vs smoker subjects regarding patients (odds ratio [OR], 0.68; 95% confidence interval [CI], 0.31–1.49; I2 = 58%) and teeth (OR, 1.71; 95% CI, 0.99–2.93; I2 = 72%). Conclusions Our findings suggest that there was no association between cigarette smoking and post-endodontic apical periodontitis, as we did not find statistical differences in the prevalence of post-endodontic AP when comparing non-smokers vs smoker subjects. Therefore, smoking should not be considered a risk factor associated with endodontic failure. Objectives This systematic review and meta-analysis aimed to assess the association of cigarette smoking with the prevalence of post-endodontic apical periodontitis in humans. Materials and Methods We searched through PubMed/Medline, Web of Science, and Scopus from inception to December 2020. Risk of bias was performed by using the Newcastle-Ottawa Scale for cross-sectional, cohort, and case-control studies. We performed the statistical analysis in Review Manager 5.3 (RevMan 5.3). Results 6 studies met the inclusion criteria for qualitative and quantitative synthesis. Statistical analysis of these studies suggests that there were no differences in the prevalence of post endodontic apical periodontitis (AP) when comparing non-smokers vs smoker subjects regarding patients (odds ratio [OR], 0.68; 95% confidence interval [CI], 0.31–1.49; I2 = 58%) and teeth (OR, 1.71; 95% CI, 0.99–2.93; I2 = 72%). Conclusions Our findings suggest that there was no association between cigarette smoking and post-endodontic apical periodontitis, as we did not find statistical differences in the prevalence of post-endodontic AP when comparing non-smokers vs smoker subjects. Therefore, smoking should not be considered a risk factor associated with endodontic failure.
Motion-based Optimum Design of a Slender Steel Footbridge and Assessment of Its Dynamic Behaviour
Javier Fernando Jiménez-Alonso,Andres Sáez 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4
The improvement of construction materials together with the current aesthetic requirements has led the modern footbridges to a continuous increase in their slenderness. For this reason, the design of their structural systems is mainly conditioned by its dynamic response under pedestrian action. For long-span footbridges, control devices are needed to prevent unacceptable dynamic responses while providing economical designs. However, for medium-span footbridges, it is still possible to control their dynamic response via the modification of their natural frequencies. In this paper, an alternative motion-based design method is first proposed and further implemented for the design of a real footbridge. The main idea of this approach is to optimally determine the structural stiffness distribution to verify an adequate comfort class, while minimizing the self-weight. Furthermore, the uncertainties of its modal parameters are considered during its design. After the construction of the footbridge, its dynamic behaviour was experimentally assessed, with satisfactory results.